use strict;
use Tk;

my $xVConsSflEmbMax0 = 1.0;
my $xVConsSflEmbMax = $xVConsSflEmbMax0;

my $mw = new MainWindow();
my $entry = $mw->Entry(
  -textvariable     => \$xVConsSflEmbMax,
  -width            => 3,
  -validate         => 'focusout',
  -validatecommand  => [\&validSub,$_[0],0,1],
  -invalidcommand   => sub {$xVConsSflEmbMax=$xVConsSflEmbMax0},
) -> pack;

MainLoop;

sub validSub {
  my ($val,$min,$max) = @_;
  $val ||= 0;
  $min ||= -1E10;
  $max ||= 1E10;
  if( $val !~ /^\d*\.?\d+$/ ) { return 0 }
  elsif (($val >= $min) and ($val <= $max)) {return 1}
  else { return 0 }
}